TY  - JOUR
AU  - I. A. Pasynkova
TI  - Letter to the editors ("The existence of families of periodic solutions of a system of $n$ second order differential equations in the resonance case'', Differencial'nye Uravnenija \textbf{5} (1969), 1984--1989)
JO  - Differencialʹnye uravneniâ
PY  - 1973
SP  - 192
VL  - 9
IS  - 1
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/DE_1973_9_1_a29/
LA  - ru
ID  - DE_1973_9_1_a29
ER  -